With this plugin, you can choose if the phone field on your WooCommerce checkout page should be required or not to fill out.
After installing the WooCommerce Remove Required Phone plugin the customer no longer has to fill out the phone number. The phone number field will of course still be visible in case the customer wants to leave the phone number anyway.
Settings for this plugin
After activating the plugin there is a setting page in the WooCommerce area where you can turn the plugin on or off, making the field required or not required.
Just tick the checkbox if require your customers to fill in the phone field on your checkout page.